FlowChart.NET中對(duì)于撤銷(xiāo)項(xiàng)目屬性的更改不會(huì)自動(dòng)記錄，要啟用撤消屬性更改，您必須明確創(chuàng)建一個(gè)ChangeItemCmd實(shí)例，并把它添加到歷史隊(duì)列。

    ChangeItemCmd構(gòu)造函數(shù)需要一個(gè)作為參數(shù)的項(xiàng)目引用，保存項(xiàng)目初始狀態(tài)用以再通過(guò)稍后撤銷(xiāo)恢復(fù)。在一個(gè)或多個(gè)項(xiàng)目的屬性分配后調(diào)用Execute方法，記錄項(xiàng)目最終的狀態(tài)再通過(guò)稍后的重做恢復(fù)。這樣的話(huà)，就可以用一個(gè)單一的記錄來(lái)保存項(xiàng)目的屬性更改，這個(gè)單一的記錄也可以作為單一的操作被撤銷(xiāo)或是重做。

C#

// Save item state
ChangeItemCmd propChange = new ChangeItemCmd(diagram.Nodes[0], "Change");

// Change properties
ShapeNode shape = (ShapeNode)diagram.Nodes[0];
shape.Text = "new text";
shape.Brush = new SolidBrush(Color.Blue);
shape.Shape = Shape.FromId("Ellipse");

// Add to history
propChange.Execute();

Visual Basic

' Save item state
Dim propChange = New ChangeItemCmd(Diagram.Nodes(0), "Change")

' Change properties
Dim shape As ShapeNode = Diagram.Nodes(0)
shape.Text = "new text"
shape.Brush = New SolidBrush(Color.Blue)
shape.Shape = MindFusion.Diagramming.Shape.FromId("Ellipse")

' Add to history
propChange.Execute()

    如果說(shuō)想要把幾個(gè)項(xiàng)目作為一個(gè)操作，需要?jiǎng)?chuàng)建一個(gè)CompositeCmd實(shí)例，以及通過(guò)調(diào)用AddSubCmd方法來(lái)添加ChangeItemCmd命令到這個(gè)復(fù)合操作上。

C#

if (diagram.Selection.Nodes.Count == 0)
    return;
 
// Make all changes seem like a single operation by
// putting them in composite Command
CompositeCmd composite = new CompositeCmd(
    diagram, "Change selection");
 
foreach (DiagramNode node in diagram.Selection.Nodes)
{
    ShapeNode shape = node as ShapeNode;
    if (shape == null)
        continue;

 
    // Save item state
    ChangeItemCmd propChange = new ChangeItemCmd(shape, "Change");
 
    // Change properties
    shape.Text = "new text";
    shape.Brush = new SolidBrush(Color.Blue);
 
    // Add to the composite
    composite.AddSubCmd(propChange);
}

// Store final state of all contained commands
composite.Execute();

Visual Basic

If diagram.Selection.Nodes.Count = 0 Then
    Return
End If

' Make all changes seem like a single operation by
' putting them in composite Command
Dim composite As CompositeCmd = New CompositeCmd( _
    diagram, "Change selection")

Dim node As DiagramNode
For Each node In diagram.Selection.Nodes

    Dim shape As ShapeNode = CType(node, ShapeNode)
    If Not shape Is Nothing Then

        ' Save item state
        Dim propChange As ChangeItemCmd = New ChangeItemCmd(shape, "Change")

        ' Change properties
        shape.Text = "new text"
        shape.Brush = New SolidBrush(Color.Blue)

        ' Add to the composite
        composite.AddSubCmd(propChange)

    End If

Next

' Store final state of all contained commands
composite.Execute()